Future treatment options for facial nerve palsy: a review on electrical stimulation devices for the orbicularis oculi muscle

Abstract

Facial nerve palsy can cause diminished eyelid closure (lagophthalmos). This occurs due to functional deficits of the orbicularis oculi muscle, potentially leading to sight-threatening complications due to corneal exposure. Current management options range from frequent lubrication with eye drops, to the use of moisture chambers and surgery. However, achieving functional restoration may not always be possible. Recent efforts have been directed towards the support of orbicularis oculi muscle function through electrical stimulation. Electrical stimulation of the orbicularis oculi muscle has been demonstrated as feasible in human subjects. This article offers a comprehensive review of electrical stimulation parameters necessary to achieve full functionality and a natural-looking eye blink in human subjects. At present, readily available portable electrical stimulation devices remain unavailable. This review lays the foundation for advancing knowledge from laboratory research to clinical practice, with the ultimate objective of developing a portable electrical stimulation device. Further research is essential to enhance our understanding of electrical stimulation, establish safety standards, determine optimal current settings, and investigate potential side effects.

Keywords: Electrical stimulation; Facial nerve palsy; Facial reanimation; Orbicularis oculi muscle.

Fig. 1

Visualization of a portable future closed-loop electrical stimulation device for patients with facial nerve palsy. Stimulus input signal can be recorded with EMG from the healthy side. Signal processing and electrical stimulation output generation should be processed in less than 33 ms. The output current should contain pulse train stimulation with a dynamic interval